Re: magnetic fields and phase noise?

[Earl W Cunningham]

Fraser, G4BJM wrote:

"Interesting Earl, the non exhaustive tests I've done indicate that it is
not due to magnetic fields."
----------
When I first told Elecraft about this problem, they sent me the new
shield for the KPA100, which didn't help.  Then they sent a mod kit that
had to do with reducing spurious RF, which didn't help.

Then I eliminated the KPA100 as being the culprit by removing it (and
installing the original cover).  Driving the amp (with only the 10 watts
available) resulted in the same problem.  Clean when barefoot (as is the
KPA100).

Then I manually keyed the amp (instead of using the KPA-100's key output)
-- no change in problem.

Then I brought my K2/100 over to a friend's QTH and tried it with his amp
-- same problem.  Separation from his amp was 6 feet.  His amp is an
Alpha 99, mine is an Alpha 76CA (both have hypersil HV transformers).

Then, at my home QTH, I set up the K2/100 in an adjacent room and ran a
coax from it to the amp in the ham shack -- no trace of the problem.

All tests were done on CW, monitoring the transmitted signal on another
receiver (FT-1000MP) using narrow (250 Hz) bandwidth.  The problem sounds
like noise on the sidebands of the transmitted CW signal extending out at
least +/-5 kHz from center freq.  There's no reason to believe that this
problem does not also exist on SSB.
==========

"But if indeed that is the case, there must be a relatively easy, if
perhaps not elegant, way of significantly improving this."
----------
It has been suggested that mu-metal shielding might alleviate the
problem.  I'm considering making mu-metal bottom and side covers for my
K2.

Another ham (W4FMS) told me he had the same problem with his K2/100 and
Alpha 87A amp.  He found that placing an aluminum cookie sheet between
the K2 and amp with only 3 feet of separation resolved the problem.

All things point in the direction of a K2 problem that is not phase
noise.

73, de Earl, K6SE
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[N2TK]

My K2/100 sits on top of my TS950SDX. If I go above about 30-50W with the K2
on 80 and 160M I have to reset my router. Was using a Belkin router. Now
using a Netgear wireless router. Both cutout. This doesn't happen all the
time - maybe 50% of the time. Been wrapping ferrite on everything, but no
difference so far. Swapped the coax cables between the 2 rigs. Router is
about 4' from the K2. I can run 100W with 950 without any problems. My amp
is in the basement about 8' away. No problem when using it with the 950 and
no problem with the K2 as long as I keep the power of the K2 below about
30-50W. Might have to move the K2 farther away and see if problem persists,
although it will be a pain to do that. Not sure yet if problem is definitely
the K2.
N2TK, Tony


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of Earl W Cunningham
Sent: Saturday, March 19, 2005 9:28 AM
To: [hidden email]; [hidden email]; [hidden email]
Subject: [Elecraft] Re: magnetic fields and phase noise?

Fraser, G4BJM wrote:

"Interesting Earl, the non exhaustive tests I've done indicate that it is
not due to magnetic fields."
----------
When I first told Elecraft about this problem, they sent me the new
shield for the KPA100, which didn't help.  Then they sent a mod kit that
had to do with reducing spurious RF, which didn't help.

Then I eliminated the KPA100 as being the culprit by removing it (and
installing the original cover).  Driving the amp (with only the 10 watts
available) resulted in the same problem.  Clean when barefoot (as is the
KPA100).

Then I manually keyed the amp (instead of using the KPA-100's key output)
-- no change in problem.

Then I brought my K2/100 over to a friend's QTH and tried it with his amp
-- same problem.  Separation from his amp was 6 feet.  His amp is an
Alpha 99, mine is an Alpha 76CA (both have hypersil HV transformers).

Then, at my home QTH, I set up the K2/100 in an adjacent room and ran a
coax from it to the amp in the ham shack -- no trace of the problem.

All tests were done on CW, monitoring the transmitted signal on another
receiver (FT-1000MP) using narrow (250 Hz) bandwidth.  The problem sounds
like noise on the sidebands of the transmitted CW signal extending out at
least +/-5 kHz from center freq.  There's no reason to believe that this
problem does not also exist on SSB.
==========

"But if indeed that is the case, there must be a relatively easy, if
perhaps not elegant, way of significantly improving this."
----------
It has been suggested that mu-metal shielding might alleviate the
problem.  I'm considering making mu-metal bottom and side covers for my
K2.

Another ham (W4FMS) told me he had the same problem with his K2/100 and
Alpha 87A amp.  He found that placing an aluminum cookie sheet between
the K2 and amp with only 3 feet of separation resolved the problem.

All things point in the direction of a K2 problem that is not phase
noise.

73, de Earl, K6SE
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[Margaret Leber]

N2TK, Tony wrote:

> My K2/100 sits on top of my TS950SDX. If I go above about 30-50W with the K2
> on 80 and 160M I have to reset my router. Was using a Belkin router. Now
> using a Netgear wireless router. Both cutout. This doesn't happen all the
> time - maybe 50% of the time. Been wrapping ferrite on everything, but no
> difference so far.

Good friend of mine who's triple DXCC (only a few shy of honor roll),
and runs QRO a lot used to have serious trouble with her DSL modem when
transmitting. After a lot of playing with ferrites she discovered that
the path of RF entry was through the "wall wart" outlet transformer
powering the DSL box.

Easy to overlook...

  -Maggie-

--
-----/___.   _)Margaret Stephanie Leber CCP, SCJP/"The art of progress /
----/(, /|  /| http://voicenet.com/~maggie SCWCD/ is to preserve order/
---/   / | / |  _   _   _    `  _  AOPA 925383/ amid change and to  /
--/ ) /  |/  |_(_(_(_/_(_/__(__(/_      K3XS / preserve change amid/
-/ (_/   '        .-/ .-/        ARRL 39280 /order."-A.N.Whitehead/
/________________(_/_(_/_______AMSAT 32844_/<[hidden email]>/

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[Don Wilhelm-3]

Tony,

Have you thought about the power supply?  Is the same power supply being
used for the K2 and the TS950SDX?  Could it be that it is not RF causing
your problem at all, but trash induced on the power line?

73,
Don W3FPR

> -----Original Message-----
>
> My K2/100 sits on top of my TS950SDX. If I go above about 30-50W
> with the K2
> on 80 and 160M I have to reset my router. Was using a Belkin router. Now
> using a Netgear wireless router. Both cutout. This doesn't happen all the
> time - maybe 50% of the time. Been wrapping ferrite on everything, but no
> difference so far. Swapped the coax cables between the 2 rigs. Router is
> about 4' from the K2. I can run 100W with 950 without any problems. My amp
> is in the basement about 8' away. No problem when using it with
> the 950 and
> no problem with the K2 as long as I keep the power of the K2 below about
> 30-50W. Might have to move the K2 farther away and see if problem
> persists,
> although it will be a pain to do that. Not sure yet if problem is
> definitely
> the K2.
> N2TK, Tony

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[G3VVT]

It may also be a good idea to try the K2 on a dummy load to see if there is  
any effect then. The entry point of the interference needs to be tracked down  
somehow to enable a cure to be made.
 
Another problem that must be getting closer with ever wider bandwidths  being
employed on broadband, we are getting closer to the point where normal  
broadband from the telcos is using part of the lower HF bands. I would guess  when
that happens there really will be trouble. I did have a chart that  laid out
the frequency span of data systems that is somewhere in my effects  I shipped
back to the UK. From memory 2Mb when used for low definition digital  video
(VHS video compatible) occupies the frequencies up to about 1.1MHz and the  34Mb
needed for a compressed full definition video system goes up to about  12MHz.
See there are 8Mb broadband systems on the loose now.
 
I wonder what frequency span they need?
 
Perhaps a list member with more knowledge on the subject could  comment.
 
Bob, G3VVT
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[Bruce Bowman-3]

Hi Earl-

Here's a wild guess to throw in the mix. Since you have tried shielding
and separation to eliminate or minimize the presumed radiated noise
path, I'm beginning to wonder if the noise source is conducted via the
power lines vs. radiated.

To validate the premise, perhaps you could conduct the same (different
room) test, but instead of running just the coax over to the K2, try
also running a large extension cord from the same outlet you would
normally use in your shack. If the noise is indeed radiated, then you
ought to see the same improved results; but if the noise is conducted,
then I would expect similar results as if the K2 & Alpha were still
co-located.

Just a thought.

Bruce, NM5B

----- Original Message -----
From: "Earl W Cunningham" <[hidden email]>
To: <[hidden email]>; <[hidden email]>;
<[hidden email]>
Sent: Saturday, March 19, 2005 9:27 AM
Subject: [Elecraft] Re: magnetic fields and phase noise?

> Fraser, G4BJM wrote:
>
> "Interesting Earl, the non exhaustive tests I've done indicate that it
> is
> not due to magnetic fields."
> ----------
> When I first told Elecraft about this problem, they sent me the new
> shield for the KPA100, which didn't help.  Then they sent a mod kit
> that
> had to do with reducing spurious RF, which didn't help.
>
> Then I eliminated the KPA100 as being the culprit by removing it (and
> installing the original cover).  Driving the amp (with only the 10
> watts
> available) resulted in the same problem.  Clean when barefoot (as is
> the
> KPA100).
>
> Then I manually keyed the amp (instead of using the KPA-100's key
> output)
> -- no change in problem.
>
> Then I brought my K2/100 over to a friend's QTH and tried it with his
> amp
> -- same problem.  Separation from his amp was 6 feet.  His amp is an
> Alpha 99, mine is an Alpha 76CA (both have hypersil HV transformers).
>
> Then, at my home QTH, I set up the K2/100 in an adjacent room and ran
> a
> coax from it to the amp in the ham shack -- no trace of the problem.
>
> All tests were done on CW, monitoring the transmitted signal on
> another
> receiver (FT-1000MP) using narrow (250 Hz) bandwidth.  The problem
> sounds
> like noise on the sidebands of the transmitted CW signal extending out
> at
> least +/-5 kHz from center freq.  There's no reason to believe that
> this
> problem does not also exist on SSB.
> ==========
>
> "But if indeed that is the case, there must be a relatively easy, if
> perhaps not elegant, way of significantly improving this."
> ----------
> It has been suggested that mu-metal shielding might alleviate the
> problem.  I'm considering making mu-metal bottom and side covers for
> my
> K2.
>
> Another ham (W4FMS) told me he had the same problem with his K2/100
> and
> Alpha 87A amp.  He found that placing an aluminum cookie sheet between
> the K2 and amp with only 3 feet of separation resolved the problem.
>
> All things point in the direction of a K2 problem that is not phase
> noise.
>
> 73, de Earl, K6SE
> _______________________________________________
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>

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[Earl W Cunningham]

Bruce, NM5B wrote:

"Here's a wild guess to throw in the mix. Since you have tried shielding
and separation to eliminate or minimize the presumed radiated noise path,
I'm beginning to wonder if the noise source is conducted via the  power
lines vs. radiated."
==========
I have never tried shielding.  W4FMS did try it and it worked for him.

The "noise source" you refer to is the magnetic field from the linear's
HV xfmr.

73, de Earl, K6SE
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[Vic K2VCO]

N2TK, Tony wrote:

> My K2/100 sits on top of my TS950SDX. If I go above about 30-50W with the K2
> on 80 and 160M I have to reset my router. Was using a Belkin router. Now
> using a Netgear wireless router. Both cutout.

Don't get me started about routers and 160/80 meters!  I have an inverted L
whose horizontal part runs right over the part of my house where the DSL router
and some ethernet cables are located.  Even 50 watts (from ANY radio) on LF
drives it nuts!  I am sort of a "fringe area" DSL customer so it doesn't take
much.  I too have tried filters, ferrites, etc.

The most fun is trying to use a logging program on my shack PC to key the rig.
When the program keys the rig, the router goes crazy and sent a flood of data
down the wireless link to the shack.  The shack computer is so busy dealing with
the packets from the network that it doesn't get around to unkeying the rig!  It
took a while before I figured out what was going on (now the router is unplugged
for contests).

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[Earl W Cunningham]

Bruce, NM5B wrote:

"I'm beginning to wonder if the noise source is conducted via the power
lines vs. radiated."
==========
Others suggested that it stopped because the K2/100 was in a different
room on an AC circuit other than the amp.

Well, the amp is on a dedicated 220 VAC line and the K2/100 is on a 110
VAC line.

73, de Earl, K6SE
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[David A. Belsley]

That dedicated 220 VAC line is likely not all that dedicated, unless
you have absolutely separate 220 VAC service coming into your shack.  
Under typical home circumstances, the 110 VAC is simply on one side of
the 220 VAC line.  So your 110 shares a buss with the 220 VAC.  
LIkewise, two separate 110 VAC lines coming from the same side of the
service are not really separate except for the breakers.

best wishes,

dave belsley, w1euy


On Mar 20, 2005, at 12:57 PM, Earl W Cunningham wrote:

> Bruce, NM5B wrote:
>
> "I'm beginning to wonder if the noise source is conducted via the power
> lines vs. radiated."
> ==========
> Others suggested that it stopped because the K2/100 was in a different
> room on an AC circuit other than the amp.
>
> Well, the amp is on a dedicated 220 VAC line and the K2/100 is on a 110
> VAC line.
>
> 73, de Earl, K6SE
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>

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[Margaret Leber]

Earl W Cunningham wrote:

> It has been suggested that mu-metal shielding might alleviate the
> problem.  I'm considering making mu-metal bottom and side covers for my
> K2.

If I were having that problem, I'd be thinking about shielding the
*source*...because it would likely affect other equipment in my shack.

  73 de Maggie K3XS

--
-----/___.   _)Margaret Stephanie Leber CCP, SCJP/"The art of progress /
----/(, /|  /| http://voicenet.com/~maggie SCWCD/ is to preserve order/
---/   / | / |  _   _   _    `  _  AOPA 925383/ amid change and to  /
--/ ) /  |/  |_(_(_(_/_(_/__(__(/_      K3XS / preserve change amid/
-/ (_/   '        .-/ .-/        ARRL 39280 /order."-A.N.Whitehead/
/________________(_/_(_/_______AMSAT 32844_/<[hidden email]>/

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[Earl W Cunningham]

Maggie, K3XS wrote:

"If I were having that problem, I'd be thinking about shielding the
*source*...because it would likely affect other equipment in my shack."
==========
Yes, indeed, the source is the HV xfmr in the amp.  No other equipment in
the shack is affected by it, including any other transmitter or
transceiver I have used to drive this amp.  I'm sure the same is true for
the thousands of amateur amps in service throughout the world.

The PLL circuit in the K2 is sensitive to magnetic fields (this is no
secret) and, rather than shielding the big amp, it makes more sense to
shield the small K2 or its PLL components.  It is felt that the inductor
in the K2's PLL circuit is picking up the hum.  Perhaps Wayne/Eric can
try using a different inductor (wound differently, shielded, whatever) to
cure the problem.

73, de Earl, K6SE
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[Stephen W. Kercel]

I've seen several mentions of mu metal in this discussion. I offer a few
thoughts for what they are worth.

Some years back, when I worked in the Electromagnetic Compatibility Group
at Oak Ridge National Laboratory, we occasionally used mu-metal. The idea
is that it directly suppresses magnetic field independent of electric
field, and is thus supposed to be an effective shield for near-field
situations where the constrained relationship between the electric and
magnetic field breaks down. (Magnetic shielding of propagating waves is not
a problem; kill off the electric field, and the magnetic field vanishes for
free.)

Mu metal is expensive, difficult to find, hard to work with if you can find
it, and if subjected to mechanical shock, it can lose its mu-ness.

Personally, I would only use it as a last desperate measure.

73,

Steve Kercel
AA4AK



At 01:54 PM 3/20/2005 -0500, you wrote:

>Earl W Cunningham wrote:
>
>>It has been suggested that mu-metal shielding might alleviate the
>>problem.  I'm considering making mu-metal bottom and side covers for my
>>K2.
>
>If I were having that problem, I'd be thinking about shielding the
>*source*...because it would likely affect other equipment in my shack.
>
>  73 de Maggie K3XS

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[S55M]

What about only changing the plates with normal materials like YaComWood's
do?
I dont know if there would be any improvment?

Adi
----- Original Message -----
From: "Stephen W. Kercel" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, March 20, 2005 10:32 PM
Subject: Re: [Elecraft] Re: magnetic fields and phase noise?


> I've seen several mentions of mu metal in this discussion. I offer a few
> thoughts for what they are worth.
>
> Some years back, when I worked in the Electromagnetic Compatibility Group
> at Oak Ridge National Laboratory, we occasionally used mu-metal. The idea
> is that it directly suppresses magnetic field independent of electric
> field, and is thus supposed to be an effective shield for near-field
> situations where the constrained relationship between the electric and
> magnetic field breaks down. (Magnetic shielding of propagating waves is
not
> a problem; kill off the electric field, and the magnetic field vanishes
for
> free.)
>
> Mu metal is expensive, difficult to find, hard to work with if you can
find

> it, and if subjected to mechanical shock, it can lose its mu-ness.
>
> Personally, I would only use it as a last desperate measure.
>
> 73,
>
> Steve Kercel
> AA4AK
>
>
>
> At 01:54 PM 3/20/2005 -0500, you wrote:
> >Earl W Cunningham wrote:
> >
> >>It has been suggested that mu-metal shielding might alleviate the
> >>problem.  I'm considering making mu-metal bottom and side covers for my
> >>K2.
> >
> >If I were having that problem, I'd be thinking about shielding the
> >*source*...because it would likely affect other equipment in my shack.
> >
> >  73 de Maggie K3XS
>
>
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[Leigh L. Klotz Jr WA5ZNU]

Lessemf.com has lots of it and other similar materials.  I tried some of
their film and didn't see an improvement with my desk lamp transformer,
but moving it to the right side of the k2 made the problem go aeay, at
least for RX.  I am still shy of TX with the lamp there.
> ----- Original Message -----
> From: "Stephen W. Kercel" <[hidden email]>
> To: <[hidden email]>
> Subject: Re: [Elecraft] Re: magnetic fields and phase noise?
>>  Mu metal is expensive, difficult to find, hard to work with if you can
> find
>>  it, and if subjected to mechanical shock, it can lose its mu-ness.
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[Stuart Rohre]

A soft steel cover might do the needed K2 shielding without the expense of
Mu Metal.  There are also mu metal type foils that are self adhesive which
could glue to existing panels for increased magnetic field shielding.

Stuart
K5KVH



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